The present invention is directed to equipment and methods for detecting seal failure for air moving equipment such as compressors. More specifically, this invention is directed to sensors and their placement for detecting oil leakage into an air or gas stream downstream from the air moving equipment.
Air compressors, fans, blowers, turbo-chargers and other air moving equipment are commonly used to provide necessary oxygen or air flow to power-producing equipment or other equipment that functions as a result of the air flow. Examples of such equipment include engines, motors, and low temperature catalytic reactions, such as fuel cells. For many applications where air moving equipment such as listed above is used, the quality or purity of the air provided to downstream equipment is not critical. However, there are a number of applications such as for certain kinds of power-producing equipment, in which any contaminants, such as particulates and chemical fumes within the air stream, must be kept low in order to have the power-producing equipment function properly and efficiently. A fuel cell is one type of power-producing equipment whose efficiency and operation can be detrimentally affected, even inhibited, by certain types of airborne contaminants.
A fuel cell has an anode and a cathode, and power is generated through a catalytic reaction. One common type of fuel cell is a hydrogen fuel cell, in which a hydrogen fuel source is directed to the anode, where the hydrogen electrons are freed, leaving positively charged ions. The freed electrons travel through an external circuit to the cathode and, in the process, provide an electrical current that can be used as a power source for external electrical circuits. The positively charged ions diffuse through the fuel cell electrolyte and to the cathode where the ions combine with the electrons and oxygen to form water and carbon dioxide, by-products of the process. To speed the cathodic reaction, a catalyst is often used.
Chemical contaminants present in either the hydrogen source or the oxygen source can inhibit the operation of the fuel cell. In fuel cell systems, the ambient air stream containing the necessary oxygen is usually compressed and/or accelerated by air moving equipment such as air compressors, flans, blowers, turbo chargers, or the like, before reaching the cathode, in order to provide the required amount of oxygen to the cathode. U.S. Pat. No. 6,432,177 (Dallas et al.), U.S. patent application Ser. No. 09/832,715, filed Apr. 11, 2001, Ser. No. 09/879,441, filed Jun. 12, 2001 and Ser. No. 10/122,647, filed Apr. 10, 2002 describe systems for removing both chemical and particulate contaminants form the air stream that provides the oxygen to a fuel cell. However, the systems described in these applications are primarily directed to removing contaminants from the air stream prior to the air stream passing through the air moving equipment. These systems are not arranged to remove contaminants that might be generated on produced by the air moving equipment.
What is needed is an arrangement to inhibit, preferably eliminate, contamination of the air stream by the air moving equipment itself and to provide for timely shutdown of the fuel cell system in the event of excess contamination of the air stream.